Rainbow Electronics MAX847 - Manual

________________General Description
The MAX847 is a complete power-supply and monitor-
ing system for two-way pagers or other low-power digi-
tal communications devices. It requires few external
components. Included on-chip are:
• A 1-cell input, 80mA output, synchronous-rectified
boost DC-DC regulator with a digitally controlled
+1.8V to +4.9V output
• Three low-noise linear-regulator outputs
• Three DAC-controlled comparators for software-
driven 3-channel A/D conversion
• SPI™-compatible serial interface
• Reset and low-battery (LBO) warning outputs
• Charger for NiCd, NiMH, lithium battery, or storage
capacitor for RF PA power or system backup
• Two 1.8
Ω
(typical) serial-controlled open-drain
MOSFET switches
An evaluation kit for the MAX847 (MAX847EVKIT) is
available to aid in design and prototyping.
Pin Configuration appears at end of data sheet.
____________________________Features
♦ 80mA Output from 1 Cell at 90% Efficiency
♦ 13µA Idle Mode™ (coast) Current
♦ Selectable Low-Noise PWM or Low-Current
Operation
♦ PWM Operating Frequency Synchronized to
Seven Times an External Clock Source
♦ Operates at 270kHz with No External Clock
♦ Automatic Backup-Battery Switchover
________________________Applications
Two-Way Pagers
GPS Receivers
1-Cell Powered Hand-Held Equipment
MAX847
1-Cell, Step-Up
Two-Way Pager System IC
________________________________________________________________ Maxim Integrated Products 1
MAX847
INPUT
SINGLE AA
ALKALINE BATTERY
0.8V TO 1.8V BATT
LX1
OUT
PGND
REG2IN
OFS
REG1
OUTPUT 2
2.85V ANALOG
LOW-BATTERY
IN/OUT
RESET
IN/OUT
SERIAL
I/O
1.8 Ω
DRIVERS
A/D INPUT
OPTIONAL
OUTPUT 1
3V LOGIC
OUTPUT 3
1V RECEIVER
TO RF PA
NiCd BATTERY STACK
OR
STORAGE CAPACITOR
REG2
REG3
NICD
AGND REF FILT
LBI
LBO
RSIN
RSO
CS
SCL
SDI
SDO
DR1
DR2
DR2IN
DRGND
CH0
SYNC
RUN
COAST RUN
____________________________________________________Typical Operating Circuit
PART
MAX847EEI -40°C to +85°C
TEMP. RANGE PIN-PACKAGE
28 QSOP
19-1349; Rev 1a; 10/98
Ordering Information
Idle Mode is a trademark of Maxim Integrated Products. SPI is a trademark of Motorola, Inc.
For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800.
For small orders, phone 1-800-835-8769.
EVALUATION KIT MANUAL
FOLLOWS DATA SHEET